With the rapid growth of mobile communication and great progress of technology, the world will move towards a fully interconnected network society where anyone or any device can acquire information and share data anytime and anywhere. It is estimated that there will be billion interconnected equipments by 2020, of which only about 10 billion may be mobile phones and tablet computers. The rest are not machines communicating with human beings but machines communicating with one another. Therefore, how to design a system to better support the Internet of Everything is a subject needing further and intensive study.
In the standard of Long Term Evolution (LTE) of the Third Generation Partnership Project (3GPP), machine-to-machine communication is called machine type communication (MTC). MTC is a data communication service that does not require human participation. Deployment of large-scale MTC user equipments can be used in such fields as security, tracking, billing, measurement and consumer electronics, and specifically relates applications, including video monitoring, supply chain tracking, intelligent meter reading, and remote monitoring. MTC requires lower power consumption and supports lower data transmission rate and lower mobility. The current LTE system is mainly for man-to-man communication services. The key to achieving the competitive scale advantages and application prospects of MTC services is that the LTE network supports low-cost MTC equipments.
In addition, some MTC user equipments need to be installed in the basement of a residential building or at a position within the protection of an insulating foil, a metal window, or a thick wall of a traditional building; MTC suffers from more serious and obvious penetration losses from air interfaces, compared to that of conventional equipment terminals (such as mobile phones and tablet computers) in LTE networks. 3GPP decides to study the project design and performance evaluation of MTC equipments with enhanced additional 20 dB coverage. It should be noted that MTC equipments located at poor network coverage areas have the following characteristics: extremely slow data transmission rates, extremely low latency requirements, and limited mobility. In view of the above characteristics of MTC, the LTE network can further optimize some signaling and/or channels to better support MTC services.
Therefore, at the 3GPP RAN #64 plenary session held in June 2014, a new MTC work item with low complexity and enhanced coverage for Rel-13 was proposed (see non-patent literature: RP-140990 New work Item on Even Lower Complexity and Enhanced Coverage LTE UE for MTC, Ericsson, NSN). In the description of this work item, an LTE Rel-13 system needs to support uplink/downlink 1.4 MHz RF bandwidth for an MTC user equipment to operate at any system bandwidth (for example, 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz). The standardization of the work item would be completed at the end of 2015.
In addition, in order to better implement the Internet of Everything, another new work item was proposed at the 3GPP RAN #69 general meeting held in September 2015 (see Non-Patent Document: RP-151621 New Work Item: NarrowBand IoT (NB-IoT)), which we refer to as Narrowband Internet of Things (NB-IoT). In the description of this item, an NB-IoT user equipment (UE) would support 180 kHz RF bandwidth for uplink and downlink.
The LTE downlink transmission is based on orthogonal frequency division multiplexing (OFDM). In the LIE system, one radio frame is divided into 10 subframes (#0 to #9). Each subframe may include, for example, 2 timeslots of equal size having a length of 0.5 ms in the time domain, and may include, for example, 12 subcarriers in the frequency domain. Each timeslot includes 7 orthogonal frequency division multiplexing (OFDM) symbols. The OFDM symbols in time and the subcarriers in frequency may be used together for defining resource elements (REs), like time-frequency grids shown in FIG. 1. Each RE corresponds to one subcarrier during an interval of one OFDM symbol. A physical resource block (PRB for short) is also defined in the LTE, where each PRB is composed of 12 consecutive subcarriers during one timeslot. Then, one subframe includes a pair of physical resource blocks, which is also called a physical resource block pair.
In the existing LTE system, the minimum granularity for resource allocation of the UE is one physical resource block or physical resource block pair. That is to say, in the same subframe, a plurality of PRBs (or PRB pairs) may be allocated to a Physical Downlink Shared Channel (PDSCH), an enhanced physical downlink control channel (EPDCCH) or a physical uplink shared channel (PUSCH). However, the NB-IoT UE supports uplink downlink 180 kHz RE bandwidth only, i.e., RF bandwidth having the size of one PRB (or PRB pair). Therefore, in NB-IoT, the physical resources of a narrowband physical shared channel cannot be allocated based on PRBs (or PRB pairs) in a frequency domain.
Therefore, a new resource allocation method for a NB-IoT physical shared channel and a corresponding mechanism for determining channel parameters are desired.